Access device

ABSTRACT

An access device places a medical article within a body space of a patient. The device has a needle section that includes an elongated body and a needle hub. The device further includes a dilator portion that has a dilator and a dilator hub. The dilator is coaxially disposed and slideable over the elongated body of the needle section. The device further includes a sheath section that has a sheath and a sheath hub. The sheath is coaxially disposed and slideable over the dilator. The device further includes a first locking mechanism operably disposed between the needle hub and the dilator hub to inhibit at least unintentional axial movement between the needle section and the dilator portion and a second locking mechanism operably disposed between the dilator hub and the sheath hub to inhibit at least unintentional axial movement between the dilator portion and the sheath section.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/747,335, filed on Jan. 22, 2013, which is a continuation of U.S.patent application Ser. No. 13/084,440, filed on Apr. 11, 2011, nowissued as U.S. Pat. No. 8,377,006, which is a continuation of U.S. Pat.application Ser. No. 12/019,598, filed on Jan. 24, 2008 and entitled“ACCESS DEVICE,” now issued as U.S. Pat. No. 7,922,696, which claims thebenefit under 35 U.S.C. §119(e) to U.S. Provisional Patent ApplicationSer. No. 60/886,443, filed Jan. 24, 2007, the entire contents of eachhereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is generally directed to access devices for introducingand delivering a catheter cannula or sheath into an artery, vein,vessel, body cavity, or drainage site.

2. Description of the Related Art

A preferred non-surgical method for inserting a catheter or vascularsheath into a blood vessel involves the use of the Seldinger technique,which includes an access needle that is inserted into a patient's bloodvessel. A guidewire is inserted through the needle and into the vessel.The needle is removed, and a dilator and sheath combination are theninserted over the guidewire. The dilator and sheath combination is theninserted a short distance through the tissue into the vessel, afterwhich the dilator and guidewire are removed and discarded. The cathetermay then be inserted through the sheath into the vessel to a desiredlocation.

A number of vascular access devices are known. U.S. Pat. Nos. 4,241,019,4,289,450, 4,756,230, 4,978,334, 5,124,544, 5,424,410, 5,312,355,5,212,052, 5,558,132, 5,885,217, 6,120,460, 6,179,823, and 6,210,332disclose examples of such devices. None of these devices, however, hasthe ease and safety of use that physicians and other healthcareproviders would prefer and, thus, there is a need for an easier-to-useand safer vascular access device, especially one that would clearlyindicate when a blood vessel has been punctured.

SUMMARY OF THE INVENTION

The present invention involves several features for an access deviceuseful for the delivery of a catheter or sheath into a space within apatient's body, such as, for example, a blood vessel or drainage site.Without limiting the scope of this invention, its more prominentfeatures will be discussed briefly. After considering this discussion,and particularly after reading the Detailed Description of the PreferredEmbodiments section below in combination with this section, one willunderstand how the features and aspects of this invention provideseveral advantages over prior access devices.

One aspect of the present invention is an access device for placing amedical article within a body space. The device has a needle sectionthat includes an elongated body and a needle hub. The elongated body hasdistal and proximal ends. The distal end is configured for insertioninto a patient's body. The proximal end is coupled with the needle hub.The device further includes a dilator portion including a dilator and adilator hub. The dilator is coaxially disposed and slideable over theelongated body of the needle section with the dilator hub being disposeddistal of the needle hub. The device further includes a sheath sectionthat has a sheath and a sheath hub. The sheath is coaxially disposed andslideable over the dilator with the sheath hub being disposed distal ofthe dilator hub. The device further includes a first locking mechanismoperably disposed between the needle hub and the dilator hub to inhibitat least unintentional axial movement between the needle section and thedilator portion when the first locking mechanism is engaged and a secondlocking mechanism operably disposed between the dilator hub and thesheath hub to inhibit at least unintentional axial movement between thedilator portion and the sheath section when the second locking mechanismis engaged. Each of said first and second locking mechanisms isconfigured to be engaged by moving the respective hubs in a non-axialmanner relative to each other. The first locking mechanism is configuredto move in a manner different from the manner in which the secondlocking mechanism is engaged.

Another aspect of the invention is an access device for placing amedical article within a body space. The device includes a needlesection including an elongated needle body with a sharp distal tip and aneedle hub from which the needle body extends. The device furtherincludes a dilator portion that includes a dilator and a dilator hub.The dilator is coaxially disposed and slideable over the needle bodywith the dilator hub being disposed distal of the needle hub. The devicefurther includes a sheath section that includes a sheath and a sheathhub. The sheath is coaxially disposed and slideable over the dilatorwith the sheath hub being disposed distal of the dilator hub. The devicefurther includes a locking mechanism disposed within the dilator andselectively operating between the needle body and the dilator. Thelocking mechanism is configured to arrest axial movement of the needlebody at least in the distal direction once the distal tip of the needlebody is drawn into the dilator portion to sheath the distal tip.

Yet another aspect of the invention is an access device for placing amedical article within a body space. The device includes a dilator hubthat has a passageway configured to receive an elongated needle. Theneedle has at least one side receptacle. The device further includes oneor more fingers or tangs disposed in the dilator hub and configured toengage with the at least one side receptacle at least when the needle isretracted through the passageway.

Additionally, a releasable interlock can be provided in some embodimentsto inhibit relative rotational movement between the needle section andthe dilator section, at least when the needle is inserted into apatient. By inhibiting such relative rotational movement, communicatingside openings in the needle and the dilator can be held in alignment toprovide a simplified passageway through which the blood or fluid mayflow. Thus, when the needle enters a blood vessel or drainage site inthe patient, blood or other body fluid quickly flows into thepassageway. The resulting blood or fluid flash is visible through thesheath section (or catheter) to indicate that the needle tip has enteredthe vessel or drainage site.

For example, but without limitation, the dilator portion or section cancomprise, in some embodiments, a dilator hub and dilator having one ormore side openings. The dilator hub may have a luer connection and areleasable locking mechanism. The releasable locking mechanism can beconfigured to releasably engage and secure the dilator section toanother part, such as the needle hub. When the needle hub and thedilator hub are releasably locked to prevent rotation therebetween, oneor more of the side openings in the dilator are aligned with one or moreside openings in the needle. The locking mechanism can also beconfigured to inhibit unintentional relative axial movement between theneedle and the dilator.

The sheath section preferably, but not necessarily, includes a sheathand sheath hub. The sheath may be made partially or completely from aclear, translucent, semi-opaque, or transparent material. Suchtransparent, translucent, semi-opaque and clear materials allow aclinician the ability to see when blood or other body fluids flows intothe needle, through the needle side opening(s), through the side dilatoropening(s), and into the viewing space between the dilator and sheath.

These and other aspects of the present invention will become readilyapparent to those skilled in the art from the following detaileddescription of the preferred embodiments, which refers to the attachedfigures. The invention is not limited, however, to the particularembodiments that are disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the inventiondisclosed herein are described below with reference to the drawings ofpreferred embodiments, which are intended to illustrate and not to limitthe invention.

FIG. 1A is a perspective view of a preferred embodiment of an accessdevice configured in accordance with the present invention.

FIG. 1B is an enlarged plan view of a needle hub, a dilator hub, and asheath hub of the access device illustrated in FIG. 1A, shown in anassembled state.

FIG. 1C is a perspective view of the assembly of the needle hub, dilatorhub and sheath hub illustrated in FIG. 1B.

FIG. 2A is side view of a needle section of the embodiment depicted inFIG. 1A.

FIG. 2B is a cross-sectional view of the needle section of theembodiment depicted in FIG. 2A taken along line A-A.

FIG. 2C is an enlarged plan view of the needle hub of the needle sectionof FIG. 2B.

FIG. 3A is a side view of the dilator portion of the embodiment depictedin FIG. 1A.

FIG. 3B is a proximal end view of the dilator portion of FIG. 3A.

FIG. 3C is a cross-sectional view of the dilator portion of theembodiment depicted in FIG. 3A, taken along line B-B.

FIG. 3D is an enlarged perspective view of the dilator hub of thedilator portion of FIG. 3A.

FIG. 4A is a side view of a sheath section of the embodiment from FIG.1A.

FIG. 4B is a proximal end view of the sheath section of FIG. 4A.

FIG. 4C is an enlarged perspective view of the sheath hub of the sheathsection of FIG. 4A.

FIG. 5 is a side view of the access device of FIG. 1A.

FIG. 6 is an enlarged cross-sectional view of a portion of theembodiment illustrated in FIG. 5 which is circled by line C-C.

FIG. 7A is a schematic, enlarged cross-sectional view of a portion ofthe needle within the dilator and illustrates an embodiment of a lockingmechanism configured in accordance with one aspect of the presentinvention.

FIGS. 7B-7D illustrate the operational steps of the locking mechanism ofFIG. 7A when arresting relative axial movement between the needle andthe dilator.

FIG. 8A is a similar cross-sectional view of a portion of a lockingmechanism which is configured in accordance with another preferredembodiment of present invention. FIG. 8A illustrates the lockingmechanism in an unlocked state.

FIG. 8B illustrates the locking mechanism of FIG. 8A in a locked state.

FIG. 9A is a schematic, enlarged cross-sectional view of a lockingmechanism configured in accordance with an additional embodiment of thepresent invention. FIG. 9A illustrates the locking mechanism in anunlocked state.

FIG. 9B illustrates the locking mechanism of FIG. 9A in a locked state.

FIG. 10A is a schematic, enlarged cross-sectional view of a lockingmechanism configured in accordance with a further embodiment of thepresent invention. FIG. 10A illustrates the locking mechanism in anunlocked state.

FIG. 10B is a cross-sectional view of the locking mechanism of FIG. 10Ataken along lines 10B-10B.

FIG. 11 is an enlarged exploded view of a dilator hub and locking plateassembly configured in accordance with an additional preferredembodiment of the present invention.

FIG. 12A is an enlarged view of an embodiment of the locking plate thatcan be used with the dilator hub shown in FIG. 11.

FIG. 12B is an enlarged view of another embodiment of the locking platethat can be used with the dilator hub shown in FIG. 11.

FIG. 12C is an enlarged view of an additional embodiment of the lockingplate that can be used with the dilator hub shown in FIG. 11.

FIGS. 13A-13D are enlarged views of perimeter shapes that the lockingplate can have in accordance with additional embodiments of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present disclosure provides an access device for the delivery of acatheter or sheath to a blood vessel or drainage site. FIG. 1illustrates an access device 102 that is configured to be inserted intoa blood vessel in accordance with a preferred embodiment of the presentinvention. While the access device is described below in this context(i.e., for vascular access), the access device also can be used toaccess and place a catheter or sheath into other locations within apatient's body (e.g., for draining an abscess) and for other purposes.

FIG. 1A is a perspective view of a preferred embodiment of an accessdevice 102. The access device 102 comprises a needle section 20, adilator portion 28, a sheath section (e.g., catheter or cannula) 58, anda guidewire 120. In preferred embodiments, the dilator portion 28 iscoaxially mounted on the needle section 20, and the sheath section 58 iscoaxially mounted on the dilator portion 28. The needle section 20comprises a needle 22 and a needle hub 21. The needle hub 21 is disposedon a proximal end of the needle 22. The dilator portion 28 comprises adilator 30 and a dilator hub 32. The dilator hub 32 is disposed on theproximal end of the dilator 30. The sheath section 58 comprises a sheath54 and a sheath hub 53. The sheath hub 53 is disposed on the proximalend of the sheath 54.

FIG. 1B is an enlarged plan view of the needle hub 21, the dilator hub32, and the sheath hub 53 of the access device illustrated in FIG. 1A,shown in an assembled state. The needle hub 21, the dilator hub 32, andthe sheath hub 53 include structures that releasably interlock the hubsso as to provide a structural and fluid connection between the needlesection 20, the dilator portion 28, and the sheath section 58.

FIG. 1C is a perspective view of the assembly of the needle hub 21,dilator hub 32 and sheath hub 53 illustrated in FIG. 1B. With referenceto FIGS. 1A and 1B, the needle section 20, dilator portion 28, andsheath section 58 are interlocked at the proximal end 110 of the accessdevice 102. In some embodiments, the releasable interlock between theneedle section 20, dilator portion 28, and sheath section 58 is a tandeminterlock where the dilator portion 28 is locked to the needle section20 at interface 101 and the sheath section 58 is locked to the dilatorportion 28 at interface 103. In additional to a structural connection,the interlocks provide a fluidic connection through the access device102.

Preferably, the needle section 20 locks to the dilator portion 28 via alock mechanism 26. The lock mechanism 26 may comprise an engagingmechanism such as hinged clips 27 with actuator sides 29. The hingedclips 27 may releasably engage and secure to corresponding catches 25 onthe dilator portion 28. In some embodiments, the clip sides 29 engageand secure the dilator portion 28 by clipping to the outer lip of a luerconnection 33 on the dilator portion 28. Although hinged clips 27 areshown, the lock member 26 may comprise any suitable engaging mechanismknown in the art. In the illustrated embodiment, as best seen in FIG.3B, the portions of the outer lip onto which the hinge clips 27 engageare flats to inhibit rotation of the needle hub 21 relative to thedilator hub 32 after a certain degree of relative rotation (e.g., 180degrees) between the needle hub 21 and the dilator hub 32.

Similarly, the sheath section 58 is secured to the dilator portion 28through a lock member 59. The sheath section 58 may, preferably,comprise a twist lock member 59 so that the user may releasably engageand secure the dilator portion 28 to the sheath section 58. In somepreferred embodiments, the dilator portion 28 comprises teeth or prongsthat are configured to mate or attach to corresponding areas on thesheath section 58. Preferably, the needle 20, dilator 28 and sheath 58are releasably locked so that a physician or user may remove sections orportions of the access device as needed for treatment.

FIG. 2A is side view of the needle section 20 of the embodiment depictedin FIG. 1A. FIG. 2B is a cross-sectional view of the needle section 20depicted in FIG. 2A taken along line A-A. As shown in both FIGS. 2A and2B, the needle section 20 has a needle 22, distal portion 106, andproximal portion 24. Preferably, the proximal portion 24 has the needlehub 21 and the lock member 26. In addition, the needle 22 may have abevel tip 108 disposed on the distal portion 106. The needle 22 mayfurther comprise one or more side openings 34.

FIG. 2C is an enlarged plan view of the needle hub 21 of the needlesection 20 of FIG. 2B. As most clearly shown in FIG. 2C, the needle hub21 may also have a luer connection 35 at the proximal portion 24 of theneedle 20. This allows the physician or healthcare provider, forexample, to introduce a guidewire 120 through the hollow portion of theluer connection 35, through the needle 22, and into a punctured vessel.Additionally, a physician or healthcare provider may also attach asyringe to the luer connection 35 to perform other procedures asdesired.

As discussed above, in preferred embodiments, the needle hub 21comprises the lock member 26. The lock member 26 may be configured tolock or secure another part such as, for example, the dilator portion 28or the sheath section 58, to the needle section 20. As shown mostclearly in FIG. 2C, the lock member 26 can comprise an engagingmechanism such as a pair of hinged clips 27, although other types oflocking mechanisms comprising tabs and/or slots can also be used.Preferably, the clip sides 29 of the hinged clips 27 can engage a lippedsurface such as the outer lip of a luer connection 33, shown in FIG. 1A.Once engaged, the clip sides 29 prevent the locked part from undesiredslipping or releasing. In certain embodiments, the clips 27 are hingedto provide a bias towards the center of the needle hub 21. Preferably,the bias prevents the secured part from slipping or disengaging from thehinged clips 27. More preferably, the bias of the hinged clips 27 can beovercome by simultaneously applying pressure on the sides 29 of theclips 27 to release, for example, the luer connection 33 from the needlehub 21. To apply the appropriate releasing pressure, a physician orhealthcare provider may, for example, place an index finger and thumb onthe sides 29 of the hinged clips 27 and apply squeezing pressure toovercome the hinge bias. The hinged clips 27 will, preferably, releaseonly when sufficient releasing pressure is applied to both clip sides29.

As shown most clearly in FIG. 2A, the needle proximal portion 24 mayhave color coding, words, or other indicia, such as a pivot or notch, toindicate to the operator the position of the bevel tip 108 relative tothe dilator 28 or the sheath section 58. For example, the arrow embeddedinto the needle hub 21 indicates the bevel up position of the needle 22and may further indicate to the healthcare provider the proper way touse the device. Also, there may be a mechanical fit between the dilator28 and the needle 22 so that the physician or healthcare provider wouldsense by feel or sound (e.g., by a click) when the needle 22 has beenrotated to change the position of the bevel tip 108.

FIG. 3A is a side view of the dilator portion 28 of the embodimentdepicted in FIG. 1A. FIG. 3B is a proximal end view of the dilatorportion 28 of FIG. 3A. FIG. 3C is a cross-sectional view of the dilatorportion 28 of the embodiment depicted in FIG. 3A, taken along line B-B.As shown, the dilator portion 28 may comprise the dilator 30 and thedilator hub 32. The dilator 30 may further comprise one or more sideopenings 111. The dilator hub 32 preferably comprises a luer connection33 with an outer lip 37. In some embodiments, the outer lip 37 can beconfigured to engage to the lock member 26 on the needle section 20illustrated in FIG. 2C.

Additionally, the dilator 30 may be coaxially mounted to the needle 22by slipping a hollow section 113 of the dilator 30 over the needle 22and releasably securing the dilator hub 32 to the needle hub 21.Preferably, the proximal end 45 of the dilator hub 32 is configured tomechanically fit and interlock with the needle lock member 26 to inhibitat least some rotational and axial motion. More preferably, the dilator30 is releasably mounted to the needle 22 so that the dilator 30 can bemounted and released, or vice versa, from a coaxial position relative tothe needle 22.

FIG. 3D is an enlarged perspective view of the dilator hub 32 of thedilator portion 28 of FIG. 3A. As is most clearly illustrated in FIG.3D, the dilator hub 32 may further comprise a locking mechanism 39. Thelocking mechanism 39 comprises one or more posts, teeth, or prongsprojecting from the dilator hub 32. The locking mechanism 39, which maybe in the form of teeth, can be configured to mate or attach tocorresponding receiving areas disposed on another part such as thesheath section 58 or the needle hub 21. This locking mechanism 39 willbe explained in greater detail in the following section.

FIG. 4A is a side view of the sheath section 58 of the embodiment fromFIG. 1A. FIG. 4B is a proximal end view of the sheath section 58 of FIG.4A. In preferred embodiments, the sheath section 58 comprises a sheath54 and a sheath hub 53. The sheath 54 may also be made partially orcompletely from clear, translucent, transparent, or semi-opaquematerial. The sheath hub 53 may further comprise winged ends 55 and alock member 59.

FIG. 4C is an enlarged perspective view of the sheath hub 53 of thesheath section 58 of FIG. 4A. Preferably, the locking member 59 maycomprise a locking or attaching structure that mates or engages with acorresponding structure. As most clearly shown in FIGS. 4B and 4C, thelocking member 59 may comprise indentations, bumps, or grooves designedto engage and secure the locking mechanism or teeth 39 on the dilatorhub 32 described above with reference to FIG. 3D.

The sheath hub 53, as best seen in FIGS. 4B and 4C, preferably isdesigned so that the locking mechanism or teeth 39 of the dilator hub 32can enter the sheath hub 53 substantially unobstructed. However, in use,once the sheath hub 53 is placed at a desired location over the dilator30, the physician or healthcare provider can twist the sheath hub 53 anddisengage or engage the locking member 59. The locking member 59 can be,for example, a protruding bump, dent, etc., that creates a mechanicalfit so that the dilator hub 32 and the sheath hub 53 are releasablyinterlocked. In the illustrated embodiment, the locking member 59 of thesheath hub 53 comprises a pair of axial arranged grooves which extendfrom a distal side of the sheath hub 53 and terminate at a protrudingbump, dent, etc. Preferably, the locked position can be disengaged bytwisting the dilator hub 32 relative to the sheath hub 53. Additionally,the sheath hub may comprise wings 55 or handle structures to allow foreasy release and removal of the sheath 54 from other parts of the accessdevice 102.

In some applications, the wings 55 are sized to provide the healthcareprovider with leverage for breaking apart the sheath hub 53. Forexample, the sheath hub 53 may comprise a thin membrane 61 connectingthe halves of the sheath hub 53. The membrane 61 is sized to keep thehalves of the sheath hub 53 together until the healthcare providerdecides to remove the sheath hub 53 from the access device. Thehealthcare provider manipulates the wings 55 to break the membrane 61and separate the sheath hub 53 into removable halves.

FIG. 5 is a side view of the access device of FIG. 1A in which theneedle section 20, dilator portion 28, and sheath section 58 areinterlocked together. In the assembly, as noted above the needle section20, dilator portion 28 and sheath section 58 are coaxially disposedabout a common longitudinal axis and form a central fluid connection.

FIG. 6 is an enlarged cross-sectional view of a portion of theembodiment illustrated in FIG. 5 which is circled by line C-C. As notedabove, the needle 22, preferably, comprises one or more side openings 34in its side wall. Additionally, the dilator may comprise one or moreside openings 111. FIG. 6, however, illustrates the alignment betweenonly one set of corresponding side openings. Other sets of side openingscan also be aligned or be misaligned depending upon the relativeorientations of the needle and the dilator.

Preferably the dilator 30 may be coaxially positioned to minimize theannular space 36 between the needle 22 and the dilator 30. The innersurface 38 of the dilator 30 need not, though it can, lie directlyagainst the outer-surface 40 of the needle 22. Preferably, the annularinterface 36 between the outer-surface 40 of the needle 22 and the innersurface 38 of the dilator 30 is minimized to inhibit the flow of bloodor its constituents (or other bodily fluids) into the annular interface36 between the dilator 30 and needle 22. Advantageously, this featureminimizes the blood's exposure to multiple external surfaces and reducesthe risk of contamination, infection, and clotting.

The sheath 54 is made partially or completely from clear, semi-opaque,translucent, or transparent material so that when blood flows into theneedle 22, (1) through the needle side opening 34, (2) through thedilator side opening 111, and (3) into an annular space 60 between thedilator 30 and the sheath 54, the physician or healthcare provider cansee the blood. This will indicate to the physician or healthcareprovider that the bevel tip 108 of the needle 22 has punctured a bloodvessel.

More preferably, the dilator 30 can be coaxially mounted to the needle22 such that at least one side opening 34 disposed on the needle 22 isrotationally aligned with at least one side opening 111 on the dilator30. In some embodiments, the needle 22 and dilator 30 may (both) havemultiple side openings 34, 111 where some or all of these side openings34, 111 can be rotationally aligned. Preferably, the needle 22 anddilator 30 maintain rotational alignment so that blood flowssubstantially unobstructed through the needle side opening 34 anddilator side opening 111.

While the side openings 34, 111 in the needle 22 and the dilator 30 arealigned in the embodiment illustrated in FIG. 6, the side openingsalternatively can overlap with each other or can be connected via aconduit. The conduit can be formed between the side openings 111, 34 inthe dilator and the needle.

In accordance with another aspect of the present invention, there isprovided an interlock or interconnection between the needle 22 and atleast one of the dilator 30 or dilator hub 32. The interlock orinterconnection inhibits the bevel tip 108 disposed on the distalportion 106 of the needle 22 from being advanced beyond the distal endof the dilator 30 once the dilator 30 has been advanced over the needle22 during use. The dilator 30 thus sheaths the sharp bevel tip 108 ofthe needle 22 to inhibit accidental needle sticks from occurring.

FIG. 7A is a schematic, enlarged cross-sectional view of a portion ofthe needle 22 within the dilator 30 and illustrates an embodiment of alocking mechanism 115 configured in accordance with one aspect of thepresent invention. When engaged, the locking mechanism 115 inhibitsmovement of the needle 22 with respect to the dilator 30 in at least onedirection. For example, the locking mechanism 115 can inhibit movementof the needle 22 at least in the distal direction once the distal tip ofthe needle body is drawn into the dilator portion to sheath the distaltip. The embodiment of the locking mechanism 115 illustrated in FIG. 7Acomprises one or more arms or tangs 117, 119, one or more bases 121,123, and one or more pivot couplings or hinges 127, 129.

The arm 117 may be axially aligned with the arm 119. Alternatively, thearms 117, 119 may be offset from each other in a radial direction. Thearms 117, 119 may be slightly rotated relative to each other or disposedat different radial locations on the inside surface of the dilator 30.The tang or arm 117, 119 may move in a direction generally transverse toa longitudinal axis of the needle body when engaging the receptacle orhole 131.

The locking mechanism 115 is illustrated on the dilator 30. However, theneedle 22 may instead comprise the locking mechanism 115. In theillustrated embodiment, the needle 22 comprises a receptacle, recess,opening, or hole 131 which interacts with the locking mechanism 115 ofthe dilator 30 when the needle 22 is sufficiently retracted into thedilator 30. The receptacle, recess, opening, or hole 131 may extendentirely around the needle 22 forming an annular groove or around only aportion of the needle 22.

For embodiments that have arms 117, 119 disposed at different radiallocations on the inside surface of the dilator 30, the needle 22 maycomprise more than one recess, opening, or hole 131. The multiplerecesses, openings, or holes 131 are disposed at radial locations aroundthe outer surface of the needle 22 that correspond to the radial spacingof the arms 117, 119 around the inside surface of the dilator 30.

The arm 117 is coupled to the base 121 via hinge 127 and rotates from anunlocked position to a locked position in a counter-clockwise direction.The arm 119 is coupled to the base 123 via hinge 129 and rotates from anunlocked position to a locked position in a clockwise direction. In theillustrated embodiment, each arm 117, 119 rotates approximately 90degrees between the unlocked position and the locked position. However,the locked position may be more or less than 90 degrees from theunlocked position. The arms 117, 119 need only rotate a sufficientamount to allow their distal ends to abut against a portion of theperimeter of the recess, opening, or hole 131.

The recess, opening, or hole 131 in the needle 22 locally increases agap located between an outside surface of the needle 22 and an insidesurface of the dilator 30 a sufficient amount to allow the arms 117, 119to rotate about their respective hinges 121, 123 and towards the lockedposition. When the arm 117 is in the locked position, the needle 22 isinhibited from relative axial movement with respect to the dilator 30 ina proximal direction. When the arm 119 is in the locked position, theneedle 22 is inhibited from relative axial movement with respect to thedilator 30 in a distal direction.

The one or more bases 121, 123 are attached to or integral with thedilator 30 and extend generally towards the coaxially aligned needle 22.The bases 121, 123 are sized so as to not interfere with movement of theneedle 22 through the dilator 30 while providing hinge points forattachment of the arms 117, 119. The arms 117, 119 are sized to allowmovement of the needle 22 through the dilator 30 when the arms 117, 119are in the unlocked position. The hinges 127, 129 permit the arms 117,119 to move from the unlocked position illustrated in FIG. 7A to alocked position illustrated in FIG. 7D.

Each arm 117, 119 can separately move to the locked position when thearm 117, 119 is axially aligned with the recess, opening, or hole 131 inthe needle 22. Once in the locked position, the hinge 127, 129 does notpermit the arm 117, 119 to move back to the unlocked position. In someembodiments, the hinges 127, 129 slightly bias the arms 117, 119 to movetowards the locked position. For example, the tang or arm 117, 119 canbe biased toward the receptacle, recess, opening, or hole 131.

FIGS. 7B-7D illustrate the operational steps of the locking mechanism115 of FIG. 7A when arresting relative axial movement between the needle22 and the dilator 30. FIG. 7B illustrates the arms 117, 119 in theunlocked position. In the unlocked position, the recess, opening, orhole 131 in the needle 22 is not axial aligned with the arms 117, 119 ofthe locking mechanism 115. A healthcare provider can move the needle 22with respect to the dilator 30 in both proximal and distal directions aslong as the recess, opening, or hole 131 in the needle 22 stays on theproximal side of the locking mechanism 115 as is illustrated in FIG. 7B.

FIG. 7C illustrates the arm 117 in the locked position. In the lockedposition, the distal end of the arm 117 is disposed within the recess,opening, or hole 131 in the needle 22. Once in the locked position, thehinge 127 does not permit the arm 117 to rotate back to the unlockedposition. When the arm 117 is in the locked position, the needle 22 maystill move in a distal direction with respect to the dilator 32 untilthe recess, opening, or hole 131 is aligned with the arm 119.

FIG. 7D illustrates both arms 117, 119 in the locked position. In thedual locked position, the distal ends of the arms 117, 119 are disposedwithin the recess, opening, or hole 131 in the needle 22. Once in thedual locked position, the hinges 127, 129 do not permit the arms 117,119 to rotate back to the unlocked position. When the arm 119 is in thelocked position, the needle 22 is inhibited from moving in the distaldirection with respect to the dilator 32.

FIG. 8A is a similar cross-sectional view of a portion of a lockingmechanism 137 which is configured in accordance with another preferredembodiment of present invention. When engaged, the locking mechanism 137inhibits movement of the needle 22 with respect to the dilator 30 inboth directions. The embodiment of the locking mechanism 137 illustratedin FIG. 8A comprises one or more pairs of v-shaped arms 135, 137. Thepairs of arms 135, 137 are disposed on diametrically opposite sides ofthe needle 22. Alternatively, the arms 135, 137 may be offset from eachother in a radial direction more or less than 180 degrees apart.

The locking mechanism 133 is illustrated on the dilator 30. However, theneedle 22 may instead comprise the locking mechanism 133. In theillustrated embodiment, the needle 22 comprises a recess, opening, orhole 139 which interacts with the locking mechanism 133 of the dilator30 when the needle 22 is sufficiently retracted into the dilator 30. Thereceptacle, recess, opening, or hole 139 may extend entirely around theneedle 22 forming an annular groove or around only a portion of theneedle 22. The needle 22 may comprise more than one recess, opening, orhole 139. The multiple recesses, openings, or holes 139 are disposed atradial locations around the outer surface of the needle 22 thatcorrespond to the radial spacing of the arms 135, 137 around the innersurface of the dilator 30.

The pairs of arms 135, 137 extend from the dilator 30 towards the needle22. Each pair of arms 135, 137 is biased towards the needle 22 and isillustrated in a compressed or unlocked state in FIG. 8A. In theunlocked state or position, the recess, opening, or hole 139 in theneedle 22 is not axial aligned with the arms 135, 137 of the lockingmechanism 133. A healthcare provider can move the needle 22 with respectto the dilator 30 in both proximal and distal directions as long as therecess, opening, or hole 139 in the needle 22 stays on the proximal sideof the locking mechanism 133 as is illustrated in FIG. 8B. Each pair ofarms 135, 137 gently presses against the outer surface of the needle 22as the needle 22 slides within the dilator 30 when the arms are in theunlocked state. Each pair of arms 135, 137 can rotate or bend to reach alocked state when the arms 135, 137 are axially aligned with the recess,opening, or hole 139.

In the illustrated embodiment, each arm of each pair of arms 135, 137rotates towards the other arm between the unlocked position and thelocked position. The arms 135, 137 need only be sufficiently biased sothat when the arms 135, 137 align with the hole 139 their distal endsabut against a portion of the perimeter of the recess, opening, or hole139. In the locked position, the distal ends of the arms 135, 137 aredisposed within the recess, opening, or hole 139 in the needle 22.

The recess, opening, or hole 139 in the needle 22 locally increases agap located between an outside surface of the needle 22 and an insidesurface of the dilator 30 a sufficient amount to allow the arms 135, 137to flex from their biased or unlocked state towards the locked position.FIG. 8B illustrates the pair of arms 135 of the locking mechanism 133 ofFIG. 8A in a locked state. When one or both of the pair of arms 135, 137is in the locked position the needle 22 is inhibited from relative axialmovement with respect to the dilator 30 in both proximal and distaldirections.

In the unlocked state Illustrated in FIG. 8A, the arms 135, 137 arebiased to contact the needle 22 but not substantially interfere withmovement of the needle 22 through the dilator 30. The arms 135, 137 aresized in their unbiased or locked state to inhibit movement of theneedle 22 through the dilator 30. The biasing of the arms 135, 137 movesthe arms 135, 137 from the unlocked position illustrated in FIG. 8A tothe locked position illustrated in FIG. 8B.

Each pair of arms 135, 137 can separately move to the locked positionwhen the pair of arms 135, 137 is axially aligned with the recess,opening, or hole 139 in the needle 22. Once in the locked position, thesize and shape of the pair of arms 135, 137 inhibit movement back to theunlocked position.

FIG. 9A is a schematic, enlarged cross-sectional view of a lockingmechanism 141 configured in accordance with an additional embodiment ofthe present invention. When engaged, the locking mechanism 141 inhibitsmovement of the needle 22 with respect to the dilator 30 in bothdirections. The embodiment of the locking mechanism 141 illustrated inFIG. 9A comprises a protrusion 143.

The locking mechanism 141 is illustrated on the dilator 30. However, theneedle 22 may instead comprise the locking mechanism 141. In theillustrated embodiment, the needle 22 comprises a recess, opening, orhole 145 which interacts with the locking mechanism 141 of the dilator30 when the needle 22 is sufficiently retracted into the dilator 30. Thereceptacle, recess, opening, or hole 145 may extend entirely around theneedle 22 forming an annular groove or around only a portion of theneedle 22. The needle 22 may comprise more than one recess, opening, orhole 145.

The protrusion 143 extends from the dilator 30 towards the needle 22 andis biased towards the needle 22. FIG. 9A illustrates the protrusion 143in a compressed or unlocked state. In the unlocked state or position,the recess, opening, or hole 145 in the needle 22 is not axial alignedwith the protrusion 143 of the locking mechanism 141. A healthcareprovider can move the needle 22 with respect to the dilator 30 in bothproximal and distal directions as long as the recess, opening, or hole145 in the needle 22 stays on the proximal side of the locking mechanism141 as is illustrated in FIG. 9A. The protrusion 143 gently pressesagainst the outer surface of the needle 22 as the needle 22 slideswithin the dilator 30 when the locking mechanism 141 is in the unlockedstate. At least a portion of the protrusion 143 can extend to reach alocked state when the protrusion 143 is axially aligned with the recess,opening, or hole 145.

The protrusion 143 need only be sufficiently biased so that when theprotrusion 143 aligns with the hole 145 its distal end abuts against aportion of the perimeter of the recess, opening, or hole 145. In thelocked position, the distal end of the protrusion 143 is disposed withinthe recess, opening, or hole 145 in the needle 22.

The recess, opening, or hole 145 in the needle 22 locally increases agap located between an outside surface of the needle 22 and an insidesurface of the dilator 30 a sufficient amount to allow the protrusion143 to flex or extend from its biased or unlocked state towards thelocked position. FIG. 9B illustrates the protrusion 143 of the lockingmechanism 141 of FIG. 9A in a locked state. When the protrusion 143 isin the locked position the needle 22 is inhibited from relative axialmovement with respect to the dilator 30 in both proximal and distaldirections.

In the unlocked state Illustrated in FIG. 9A, the protrusion 143 isbiased to contact the needle 22 but not substantially interfere withmovement of the needle 22 through the dilator 30. The protrusion 143 issized in its unbiased or locked state to inhibit movement of the needle22 through the dilator 30. The biasing of the protrusion 143 moves thedistal end of the protrusion from the unlocked position illustrated inFIG. 9A to the locked position illustrated in FIG. 9B.

FIG. 10A is a schematic, enlarged cross-sectional view of a lockingmechanism 147 configured in accordance with a further embodiment of thepresent invention. When engaged, the locking mechanism 141 inhibitsmovement of the needle 22 with respect to the dilator 30 in bothdirections. The embodiment of the locking mechanism 141 illustrated inFIG. 10A comprises a detent 149.

The locking mechanism 147 is illustrated on the dilator 30. However, theneedle 22 may instead comprise the locking mechanism 147. In theillustrated embodiment, the needle 22 comprises a recess, opening, orhole 151 which interacts with the locking mechanism 149 of the dilator30 when the needle 22 is sufficiently retracted into the dilator 30. Thereceptacle, recess, opening, or hole 151 may extend entirely around theneedle 22 forming an annular groove or around only a portion of theneedle 22. The needle 22 may comprise more than one recess, opening, orhole 151.

The detent 149 extends from the dilator 30 towards the needle 22 andrides in an axial groove in the needle 22. The proximal end of thegroove connects with the hole 151. FIG. 10A illustrates the detent 149in an unlocked state. In the unlocked state or position, the recess,opening, or hole 151 in the needle 22 is not axial aligned with thedetent 149 of the locking mechanism 147. A healthcare provider can movethe needle 22 with respect to the dilator 30 in both proximal and distaldirections as long as the recess, opening, or hole 151 in the needle 22stays on the proximal side of the locking mechanism 147 as isillustrated in FIG. 10A. The detent 149 rides in the groove in the outersurface of the needle 22 as the needle 22 slides within the dilator 30when the locking mechanism 147 is in the unlocked state. The detent 149and groove further inhibit relative rotation of the needle 22 withrespect to the dilator 30. The detent 149 reaches a locked state whenthe detent 149 is axially aligned with the recess, opening, or hole 151.

The recess, opening, or hole 151 in the needle 22 locally increases agap located between a bottom surface of the groove in the needle 22 andan inside surface of the dilator 30 a sufficient amount to allow thedetent 149 to flex or extend from a biased or unlocked state towards thelocked position. FIG. 10B illustrates the detent 149 of the lockingmechanism 147 in the unlocked state. While not illustrated, when thedetent 149 is in the locked position the needle 22 is inhibited fromrelative axial movement with respect to the dilator 30 in both proximaland distal directions.

In the unlocked state illustrated in FIGS. 10A and 10B, the detent 149is slightly biased to contact the bottom of the groove in the needle 22but not to substantially interfere with movement of the needle 22through the dilator 30. The detent 149 is sized in its unbiased orlocked state to inhibit movement of the needle 22 through the dilator30.

FIG. 11 is an enlarged exploded view of a dilator hub and locking plateassembly 153 configured in accordance with an additional preferredembodiment of the present invention. The assembly 153 includes a dilatorhub 155 and one or more fingers or tangs 162. The one or more fingers ortangs 162 are spaced and sized such that they enter or snap into theside hole or holes in the needle 22 when the needle 22 is retracted. Insome applications, a single finger or tang 162 is employed.

The one or more fingers or tangs 162 inhibit the bevel tip 108 disposedon the distal portion 106 of the needle 22 from being advanced beyondthe distal end of the dilator 30 once the dilator 30 has been advancedover the needle 22 during use. The dilator 30 thus sheaths the sharpbevel tip 108 of the needle 22 to inhibit accidental needle sticks fromoccurring.

The one or more fingers or tangs 162 may be integrated into the dilatorhub 155 or part of a separate structure that is combined with thedilator hub 155. In the embodiment illustrated in FIG. 11, the one ormore fingers or tangs 162 are formed on a separate structure in the formof a locking plate 157(a)-(c). In this way, the locking plate 157(a)-(c)comprises the one or more fingers or tangs 162. Exemplary locking plates157(a)-(c) are illustrated in FIGS. 12A-12C. Of course the structure ofthe locking plates 157(a)-(c) is not limited to the illustratedembodiments. For example, the locking plate 157 could be configured toinclude one or more of the locking mechanisms illustrated in FIGS. 7A,8A, 9A, and 10A. For embodiments that have the one or more fingers ortangs 162 integrated into the dilator 155, the assembly 153 need notinclude a separate locking plate 157.

The dilator hub 155 and locking plate 157(a)-(c) may be separatelymanufactured and assembled as is illustrated in FIG. 11 or manufacturedas a unitary assembly. The dilator hub 155 and locking plate 157(a)-(c)may be manufactured from the same or different materials, including, forexample, plastics, metals, combinations thereof, and other materials.The locking plate 157 can be co-molded within the dilator hub 155 toform a unitary assembly. For example, a metal locking plate 157 can bemolded into a plastic dilator hub 155. As explained above, a separatestructure in the form of the locking plate 157 is for the In someapplications, the locking plates 157(a)-(c) are movable with respect tothe dilator hub 155 between unlocked and locked positions.

The dilator hub 155 is similar to the dilator hub 32 illustrated in FIG.3A except that the dilator hub 155 is configured to slideingly receivethe one or more locking plates 157(a)-(c) through one or more slots158(a)-(c). While multiple locking plates 157(a)-(c) and slots158(a)-(c) are illustrated in FIG. 11, only a single locking plate157(a)-(c) and slot 158(a)-(c) can inhibit movement of the needle 22. Insome applications, multiple locking plates 157(a)-(c) are inserted fromdifferent sides of the dilator hub 155 so that the fingers or tangs 162from the locking plates 157(a)-(c) combine to completely surround theneedle 22 even though separately the tangs or fingers 162 of eachlocking plate 157 would not surround the needle 22. The slot 158(a)-(c)need not be arranged perpendicular to the axis of the needle 22 orlocated in a specific side or surface of the dilator hub 155 as isillustrated in FIG. 11. Multiple locking plates 157(a)-(c) may beinserted into a single slot 158.

A healthcare provider slides the locking plate 157(a)-(c) from anunlocked position to a locked position relative to the dilator hub 155.The locking plate 157(a)-(c) may be completely removed from the slot158(a)-(c) or partially inserted into the slot 158(a)-(c) when in theunlocked position. When the locking plate 157(a)-(c) is in the lockedposition, the needle 22 is disposed in a hole or center region 160 ofthe locking plate 157(a)-(c). The small size of the guide wire 120inside the needle 22 does not affect the locking feature of theassembly.

FIG. 12A is an enlarged view of an embodiment of a locking plate 159that can be used with the dilator hub 155 shown in FIG. 11. The lockingplate 159 comprises a hole 160 surrounded by one or more fingers ortangs 162. An opening 164 extends from an outer perimeter of the lockingplate 159 to the hole 160. The opening 164 permits the locking plate 159to be inserted into the dilator hub 155 after the needle 22 is insertedthrough the dilator hub 155. The needle 22 passes through the opening164 as the locking plate 159 is slid into the slot 158 and eventuallyenters the hole 160 when the locking plate 159 is in the locked positionor state. Since the one or more fingers or tangs 162 do not extendentirely around the needle 22 when the needle 22 is inserted through thedilator hub 155, preferably the one or more side holes, receptacles, orannular groove in the needle 22 extend or are spaced radially about theneedle 22 so that one of the fingers or tangs 162 will catch the one ormore side holes, receptacles, or annular groove when the one or moreside holes, receptacles, or annular groove passes through the lockingplate 159.

When in the locked position, at least one of the distal ends of thefingers or tangs 162 extends a sufficient distance toward the needle 22to enter a hole or slot in the needle 22 and inhibit further axialmovement of the needle 22. In some applications, the hole or slot in theneedle 22 falls onto the finger or tang 162. The hole may be the one ormore side openings 34 in the side wall of the needle 22 or thereceptacle, recess, opening, or hole 131, 139, 145, and 151 illustratedin, for example, FIGS. 7A, 8A, 9A, and 10A, respectively. In someapplications, the receptacle, recess, opening, or hole 131, 139, 145,and 151 is the same structure as the one or more side openings 34.

FIG. 12B is an enlarged view of another embodiment of a locking plate161 that can be used with the dilator hub 155 shown in FIG. 11. Thelocking plate 161 comprises a hole 160 surrounded by one or more fingersor tangs 162. An opening 164 extends from an outer perimeter of thelocking plate 161 to the hole 160. The opening 164 permits the lockingplate 161 to be inserted into the dilator hub 155 after the needle 22 isinserted through the dilator hub 155. The needle 22 passes through theopening 164 as the locking plate 161 is slid into the slot 158 andeventually enters the hole 160 when the locking plate 161 is in thelocked position or state.

Since the one or more fingers or tangs 162 do not extend entirely aroundthe needle 22 when the needle 22 is inserted through the dilator hub155, preferably the one or more side holes, receptacles, or annulargroove in the needle 22 extend or are spaced radially about the needle22 so that one of the fingers or tangs 162 will catch the one or moreside holes, receptacles, or annular groove when the one or more sideholes, receptacles, or annular groove passes through the locking plate161.

FIG. 12C is an enlarged view of an additional embodiment of a lockingplate 163 that can be used with the dilator hub 155 shown in FIG. 11.The locking plate 163 comprises a hole 160 surrounded by one or morefingers or tangs 162. Unlike the embodiments illustrated in FIGS. 12Aand 12B, the locking plate 163 has a closed pedal 166 instead of anopening. Further, the fingers or tangs 162 extend all the way around theneedle 22. When the needle 22 passes through the dilator hub 155, theside hole in the needle 22 will be caught by the fingers or tangs 162irrespective of whether the needle 22 is rotated relative to the dilatorhub 155.

In this embodiment, the locking plate 163 is inserted in the dilator hub155 before the needle 22 is axially inserted into the dilator hub 155.Since the fingers or tangs 155 extend entirely around the needle 22, asheath or mandrel temporarily covers the side hole in the needle 22 toallow the needle 22 to be assembled through the dilator hub 155. Onceassembled, the sheath or mandrel is removed from the needle 22.

FIGS. 13A-13D are enlarged views of perimeter shapes that the lockingplate 157(a)-(c) can have in accordance with additional embodiments ofthe present invention. Any of the perimeter shapes illustrated in FIGS.13A-D can be added to any of the locking plates 159, 161, 163. Of coursethe perimeter shapes are not limited to the illustrated embodiments. Insome applications, the perimeter shape is selected to prevent thelocking plate 157 from being removed from the dilator hub 155 or merelyinhibit the locking plate 157 from falling out of the dilator hub 155.

The slot 158(a)-(c) in the dilator hub 155 would include correspondingshaped surfaces which engage with the perimeter shape 165, 167, 169 ofthe locking plate to inhibit the healthcare provider from removing thelocking plate from the dilator hub 155 once the locking plate 157 hasbeen slid to the locked position. In this way, the healthcare provideris prevented from accidently removing the locking plate and releasingthe needle 22.

The embodiments herein described are comprised of conventional,biocompatible materials. For example, the needle preferably consists ofa rigid polymer or a metal such as stainless steel, nitinol, or thelike. The other elements can be formed of suitable polymeric materials,such as nylon, polyethylene, high-density polyethylene, polypropylene,fluoropolymers and copolymers such as perfluoro (ethylene-propylene)copolymer, polyurethane polymers or co-polymers.

As noted above, the present access device can be used to place acatheter at other locations within a patient's body. Thus, for example,but without limitation, the access device can be used with a variety ofcatheters to drain fluids from abscesses, to drain air from apneumotorax, and to access the peritoneal cavity. In such applications,body fluids flow into the viewing space to indicate when the needle hasbeen properly placed.

Although this invention has been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. In addition, while a number of variations of the invention havebeen shown and described in detail, other modifications, which arewithin the scope of this invention, will be readily apparent to those ofskill in the art based upon this disclosure. It is also contemplatedthat various combinations or subcombinations of the specific featuresand aspects of the embodiments may be made and still fall within thescope of the invention. Accordingly, it should be understood thatvarious features and aspects of the disclosed embodiments can becombined with or substituted for one another in order to form varyingmodes of the disclosed invention. Thus, it is intended that the scope ofthe present invention herein disclosed should not be limited by theparticular disclosed embodiments described above, but should bedetermined only by a fair reading of the disclosure.

What is claimed is:
 1. An access device for placing a medical articlewithin a body space, comprising: a needle section including an elongatedbody and a needle hub, the elongated body having distal and proximalends, the distal end being configured for insertion into a patient'sbody, the proximal end being coupled with the needle hub; a dilatorportion including a dilator and a dilator hub, the dilator beingcoaxially disposed and slideable over the elongated body of the needlesection with the dilator hub being disposed distal of the needle hub; asheath section comprising a sheath and a sheath hub, the sheath beingcoaxially disposed and slideable over the dilator with the sheath hubbeing disposed distal of the dilator hub; a first locking mechanismoperably disposed between the needle hub and the dilator hub to inhibitat least unintentional axial movement between the needle section and thedilator portion when said first locking mechanism is engaged; and asecond locking mechanism operably disposed between the dilator hub andthe sheath hub to inhibit at least unintentional axial movement betweenthe dilator portion and the sheath section when said second lockingmechanism is engaged; wherein each of said first and second lockingmechanisms is configured to be engaged by moving the respective hubs ina non-axial manner relative to each other, and wherein the first lockingmechanism is configured to move in a manner different from the manner inwhich the second locking mechanism is engaged.
 2. The access device ofclaim 1, wherein the second locking mechanism is configured to beengaged by rotating the dilator hub relative to the sheath hub abouttheir common axis.
 3. The access device of claim 2, wherein the secondlocking mechanism comprises at least one key post and at least one keyhole, and at least one of the dilator hub and the sheath hub includesthe key post and the other one includes the corresponding key hole. 4.The access device of claim 2, wherein the second locking mechanismincludes a plurality of key posts disposed on the dilator hub and aplurality of key holes disposed on the sheath hub.
 5. The access deviceof claim 1, wherein the first locking mechanism is configured to beengaged by pivoting a member of the first locking mechanism about anaxis lying generally transverse to an axis common to the needle sectionand the dilator portion.
 6. The access device of claim 5, wherein thefirst locking mechanism includes a first clip pivotally attached to oneof the needle hub and the dilator hub, the first clip including a tangdisposed on an outer end that is configured and oriented to engage acorresponding catch disposed on the other one of the needle hub and thedilator hub.
 7. The access device of claim 6, wherein the first clipincludes an actuating side and a pivot point, the pivot point lyingbetween the actuating side and the tang.
 8. The access device of claim6, wherein the first locking mechanism includes a second clip pivotallyattached to the same hub to which the first clip is attached, the secondclip being disposed on said hub in a position generally diametricallyopposed to the first clip.
 9. The access device of claim 6, wherein thecorresponding catch and clip have sufficient widths to inhibit relativerotation between the dilator hub and the needle hub.
 10. An accessdevice for placing a medical article within a body space, comprising: aneedle section including an elongated needle body with a sharp distaltip and a needle hub from which the needle body extends; a dilatorportion including a dilator and a dilator hub, the dilator beingcoaxially disposed and slideable over the needle body with the dilatorhub being disposed distal of the needle hub; a sheath section comprisinga sheath and a sheath hub, the sheath being coaxially disposed andslideable over the dilator with the sheath hub being disposed distal ofthe dilator hub; and a locking mechanism disposed within the dilator andselectively operating between the needle body and the dilator, thelocking mechanism being configured to arrest axial movement of theneedle body at least in the distal direction once the distal tip of theneedle body is drawn into the dilator portion to sheath the distal tip.11. The access device of claim 10, wherein the locking mechanismcomprises a receptacle and a tang biased toward the receptacle, thereceptacle being formed on either the outer surface of the needle bodyor an inner surface of the dilator hub, and the tang extending from theother one of the needle body outer surface and the dilator hub innersurface.
 12. The access device of claim 11, wherein the receptaclecomprises a hole in the needle body.
 13. The access device of claim 11,wherein the receptacle comprises an annular groove about the needlebody.
 14. The access device of claim 11 additionally comprising a secondtang oriented to arrest axial movement of the needle body in a proximaldirection.
 15. The access device of claim 14, wherein the first andsecond tangs engage said receptacle when the distal tip of the needlebody is sufficiently withdrawn into the dilator portion.
 16. The accessdevice of claim 14, wherein the locking mechanism includes anotherreceptacle disposed so as to receive the second tang when the distal tipof the needle body is withdrawn into the dilator portion.
 17. The accessdevice of claim 11, wherein the tang is attached to the dilator hub by apivot coupling.
 18. The access device of claim 11, wherein the tang isconfigured to move in a direction generally transverse to a longitudinalaxis of the needle body when engaging the receptacle.
 19. An accessdevice for placing a medical article within a body space, comprising: adilator hub having a passageway configured to receive an elongatedneedle, the needle having at least one side receptacle; and one or morefingers or tangs disposed in the dilator hub and configured to engagewith the at least one side receptacle at least when the needle isretracted through the passageway.
 20. The access device of claim 19further comprising a locking plate and a slot, the slot being disposedin the dilator hub so as to slideingly receive the locking plate,wherein the one or more fingers or tangs are disposed on said lockingplate.